U.S. patent number 6,884,839 [Application Number 10/148,428] was granted by the patent office on 2005-04-26 for aqueous primary dispersions and coating matters, a method for producing same and the use thereof.
This patent grant is currently assigned to BASF Coatings AG. Invention is credited to Maximilian Bendix, Wolfgang Bremser, Reinhold Clauss, Ralf Nickolaus.
United States Patent |
6,884,839 |
Bendix , et al. |
April 26, 2005 |
Aqueous primary dispersions and coating matters, a method for
producing same and the use thereof
Abstract
Aqueous primary dispersions and coating materials comprising
dispersed and/or emulsified, solid and/or liquid polymer particles
and/or dispersed solid core shell particles having a
diameter.ltoreq.500 nm preparable by controlled free-radical
microemulsion or miniemulsion polymerization of A) at least one
olefinically unsaturated monomer and B) at least one olefinically
unsaturated monomer which is different than the olefinically
unsaturated monomer (A) and has the general formula I: R.sup.1
R.sup.2 C.dbd.CR.sup.3 R.sup.4 (I), in which the radicals R.sup.1,
R.sup.2, R.sup.3 and R.sup.4 independently of one another are
hydrogen atoms or substituted or unsubstituted alkyl, cycloalkyl,
alkylcycloalkyl, cycloalkylalkyl, aryl, alkylaryl, cycloalkylaryl,
arylalkyl or arylcycloalkyl radicals, with the proviso that at
least two of the variables R.sup.1, R.sup.2, R.sup.3 and R.sup.4
are substituted or unsubstituted aryl, arylalkyl or arylcycloalkyl
radicals, especially substituted or unsubstituted aryl radicals;
and in the presence of (C) at least one hydrophobic cross-linking
agent for the copolymer resulting from the starting products (A)
and (B).
Inventors: |
Bendix; Maximilian (Munster,
DE), Clauss; Reinhold (Steinfurt, DE),
Nickolaus; Ralf (Drensteinfurt, DE), Bremser;
Wolfgang (Munster, DE) |
Assignee: |
BASF Coatings AG (Munster,
DE)
|
Family
ID: |
7932386 |
Appl.
No.: |
10/148,428 |
Filed: |
May 29, 2002 |
PCT
Filed: |
November 08, 2000 |
PCT No.: |
PCT/EP00/11006 |
371(c)(1),(2),(4) Date: |
May 29, 2002 |
PCT
Pub. No.: |
WO01/42310 |
PCT
Pub. Date: |
June 14, 2001 |
Foreign Application Priority Data
|
|
|
|
|
Dec 11, 1999 [DE] |
|
|
199 59 923 |
|
Current U.S.
Class: |
524/570;
427/372.2; 525/61; 525/194; 525/192; 427/384; 524/804; 524/502 |
Current CPC
Class: |
C08G
18/0866 (20130101); C09D 175/04 (20130101); C08G
18/6229 (20130101); C08F 2/22 (20130101); C08G
18/807 (20130101); C08F 220/18 (20130101); C08F
220/14 (20130101); C08F 220/14 (20130101); C08F
220/1804 (20200201); C08F 212/08 (20130101); C08F
220/281 (20200201); C08F 220/18 (20130101); C08F
212/08 (20130101); C08F 220/281 (20200201); C08F
212/32 (20130101); C08F 220/18 (20130101); C08F
212/08 (20130101); C08F 220/281 (20200201); C08F
212/32 (20130101); C08F 220/14 (20130101); C08F
220/1804 (20200201); C08F 212/08 (20130101); C08F
220/281 (20200201) |
Current International
Class: |
C08G
18/08 (20060101); C08F 2/12 (20060101); C08G
18/00 (20060101); C09D 175/04 (20060101); C08F
2/22 (20060101); C08G 18/80 (20060101); C08G
18/62 (20060101); C08F 220/18 (20060101); C08F
220/14 (20060101); C08F 220/00 (20060101); C08F
210/14 () |
Field of
Search: |
;524/502,804,570
;525/61,192,194 ;427/372.2,384 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2004988 |
|
Dec 1989 |
|
CA |
|
2103595 |
|
Jan 1992 |
|
CA |
|
2086156 |
|
Dec 1992 |
|
CA |
|
2127919 |
|
Jul 1994 |
|
CA |
|
2181934 |
|
Jul 1996 |
|
CA |
|
2259559 |
|
Mar 1997 |
|
CA |
|
2355620 |
|
Jul 2000 |
|
CA |
|
196 28 142 |
|
Jan 1998 |
|
DE |
|
196 28 143 |
|
Jan 1998 |
|
DE |
|
35 46 594 |
|
Dec 1999 |
|
DE |
|
358221 |
|
Sep 1989 |
|
EP |
|
401565 |
|
May 1990 |
|
EP |
|
0 401 565 |
|
May 1990 |
|
EP |
|
498583 |
|
Jan 1992 |
|
EP |
|
0 644 205 |
|
Aug 1994 |
|
EP |
|
732359 |
|
Mar 1996 |
|
EP |
|
755946 |
|
Jul 1996 |
|
EP |
|
WO9106535 |
|
May 1991 |
|
WO |
|
WO92/13903 |
|
Aug 1992 |
|
WO |
|
WO9222355 |
|
Dec 1992 |
|
WO |
|
WO9322351 |
|
Nov 1993 |
|
WO |
|
WO 95/34586 |
|
Dec 1995 |
|
WO |
|
WO96/15157 |
|
May 1996 |
|
WO |
|
WO 97/49739 |
|
Dec 1997 |
|
WO |
|
WO98/01478 |
|
Jan 1998 |
|
WO |
|
WO98/37104 |
|
Aug 1998 |
|
WO |
|
WO9915597 |
|
Jan 1999 |
|
WO |
|
WO99/10413 |
|
Apr 1999 |
|
WO |
|
WO 02/064652 |
|
Aug 2002 |
|
WO |
|
WO 02/064692 |
|
Aug 2002 |
|
WO |
|
Other References
BASF Coatings AG, US application No. 10/018,703 filed Dec. 13,
2001, pp. 1-79. .
Abstract of JP 07-316242, Derwent Assession No. 1996-05619, Dec. 5,
1995. .
Translation of WO 02/064692, U.S. application No. 10/250,694 filed
on Jul. 3, 2003. .
Translation of WO 02/064652, U.S. application No. 10/250,586 filed
on Jul. 2, 2003. .
BASF Coatings AG, et al., USSN 09/263,426, Feb. 16, 1998, pp. 1-32.
.
I. Mangels, et al., USSN 10/088,376, filed Mar. 11, 2002, pp.
1-109. .
H. Rink, et al., USSN 10/149,607, filed Feb. 14, 2002, pages. .
U. Meisenburg, et al., USSN 09/926,532, filed Nov. 16, 2001, pp.
1-Abstract. .
H. Rink, et al., USSN 09/830,694, filed Apr. 27, 2001, pp. 1-83.
.
W. Locken, et al., USSN 09/856,951, filed May 29, 2001, pp. 1-90.
.
H. Baumgart, et al., USSN 09/049,656, filed Feb. 13, 2002, pp.
1-54. .
English Translation for BASF Corporation, et al., USSN 10/169,473
filed Jun. 28, 2002 IN-5600. .
English Translation for BASF Corporation, et al., USSN 10/148,427
filed May 29, 2002 IN-5585. .
English Translation for BASF Corporation, et al., USSN 10/148,295
filed May 29, 2002 IN-5594. .
English Translation for BASF Corporation, et al., USSN 10/239,938
filed Sep. 26, 2002 IN-5622. .
Ramesh, et al., 10/455,066, filed Jun. 5, 2003. .
Bremser, 10/018,352, filed Dec. 7, 2001. .
Bremser, 10/018,351, filed Dec. 7, 2001. .
Bremser, 10/018,350, filed Dec. 7, 2001. .
Derwent Accession No.1996-094214, English Abstract for JP08003208.
.
Derwent Accession No. 1986-152526, English Abstract for NIPPON,
JP61085417. .
Derwent Accession No. English Abstract for JP11217409. .
English Abstract for, Dalibor, DE 3546594, filed Dec. 10, 1987.
.
English Abstract for Grutter, EP 358 221, filed Mar. 14, 1990.
.
English Abstract for Knoll, et al., EP 732 359, filed Sep. 18,
1996..
|
Primary Examiner: Wu; David W.
Assistant Examiner: Sastri; Satya
Claims
What is claimed is:
1. An aqueous composition comprising a polymer having a diameter
.ltoreq.500 nm comprising a controlled free-radical microemulsion
or miniemulsion polymerization product of A) at least one
olefinically unsaturated monomer and B) at least one olefinically
unsaturated monomer that is different than the olefinically
unsaturated monomer (A) and has the general formula I
2. The aqueous composition of claim 1, wherein the aryl radical is
one of a phenyl radical and a naphthyl radical.
3. The aqueous composition of claim 1, wherein the substituent in
at least one of R.sup.1, R.sup.2, R.sup.3, and R.sup.4 is one of an
electron-withdrawing atom, an electron-donating atom, and an
organic radical.
4. The aqueous composition of claim 3, wherein the substituent is
at least one of a halogen atom, a nitrile, a nitro group, an at
least partially halogenated alkyl radical, an at least partially
halogenated cycloalkyl radical, an at least partially halogenated
alkylcycloalkyl radical, an at least partially halogenated
cycloalkylalkyl radical, an at least partially halogenated aryl
radical, an at least partially halogenated alkylaryl radical, an at
least partially halogenated cycloalkylaryl radical, an at least
partially halogenated arylalkyl radical, and an at least partially
halogenated arylcycloalkyl radical, an aryloxy radical, a alkyloxy
radical, and a cycloalkyloxy radical, an arylthio radical, a
alkylthio radical, a cycloalkylthio radical, a primary amino group,
a secondary amino group, and a tertiary amino group.
5. The aqueous composition of claim 1, wherein the crosslinking
agent is at least one of a blocked polyisocyanate, a
tris(alkoxycarbonylamino)triazine, and a fully etherified amino
resin.
6. The aqueous composition of claim 1, wherein the monomers (A) and
(B) are copolymerized in the presence of at least one further
hydrophobic compound (D) other than the crosslinking agent (C).
7. The aqueous composition of claim 6, wherein the further
hydrophobic compound is water-insoluble and is one of a polymer, an
oligomer, and a substances of low molecular mass.
8. The aqueous composition of claim 7, wherein the further
hydrophobic compound is at least one of: i) an ester of an
.alpha.,.beta.-monoolefinically unsaturated carboxylic acid, having
3 to 6 carbon atoms, with an alcohol having 12 to 30 carbon atoms
in the alkyl radical; ii) an ester of a) at least one of a vinyl
alcohol and an allyl alcohol with b) at least one of an
alkanemonocarboxylic acid, an alkanemonosulfonic acid, and an
alkanemonophosphonic acid having 12 to 30 carbon atoms in the
molecule; iii) an amide of an .alpha.,.beta.-monoolefinically
unsaturated carboxylic acid having 3 to 6 carbon atoms with an
alkylamine having 12 to 30 carbon atoms in the alkyl radical; iv) a
macromonomer comprising an olefinically unsaturated compound having
on average at least one olefinically unsaturated group in the
molecule; v) a polysiloxane macromonomer having on average at least
one olefinically unsaturated group in the molecule; vi) at least
one of an oligomeric reaction product and a polymeric reaction
product of at least one of addition polymerization,
polycondensation, and polyaddition; vii) a water-insoluble
molecular weight regulator; viii) at least one of an alkanol and an
alkylamine having at least 12 carbon atoms in the alkyl radical;
ix) at least one of an organosilane and an organosiloxane; x) at
least one of a vegetable oil, an animal oil, a semisynthetic oil,
and a synthetic oil; and xi) a hydrophobic dye.
9. The aqueous composition of claim 1, wherein the monomers (A) and
(B) are copolymerized in the presence of at least one of an
emulsifier and a protective colloid.
10. The aqueous composition of claim 1, wherein monomer (A) is at
least one of: a1) a (meth)acrylic ester; a2) a monomer that carries
per molecule at least one hydroxyl group; a3) a monomer that
carries per molecule at least one acid group that can be converted
into a corresponding acid anion group; a4) a vinyl ester of an
alpha-branched monocarboxylic acid having 5 to 18 carbon atoms in
the molecule; a5) a reaction product of a (meth)acrylic acid with a
glycidyl ester of an alpha-branched monocarboxylic acid having from
5 to 18 carbon atoms per molecule; a6) at least one of a cyclic
olefin and an acyclic olefin; a7) a (meth)acrylamide; a8) a monomer
containing at least one epoxide group; a9) a vinylaromatic
hydrocarbon; a10) a nitrile; a11) a vinyl compound; a12) an allyl
compound; a13) a polysiloxane macromonomer having a number-average
molecular weight Mn of from 1,000 to 40,000 and containing on
average from 0.5 to 2.5 ethylenically unsaturated double bonds per
molecule; and a14) an acryloyloxysilane-containing vinyl monomer
comprising a reaction product of a material and at least one of
methacrylic acid and a hydroxyalkyl ester of (meth)acrylic acid,
wherein the material comprises a reaction product of a
hydroxy-functional silane and epichlorohydrin; with the proviso
that the monomer (a3) is not used as the sole monomer (A).
11. The aqueous composition of claim 1, wherein at least one
monomer (A) contains reactive functional groups that are able to
undergo a crosslinking reaction with a complementary reactive
functional group of the crosslinking agent (C).
12. The aqueous composition of claim 1, wherein the controlled
free-radical microemulsion or miniemulsion polymerization is
initiated by an initiator that forms free radicals and is at least
one of water-soluble and oil-soluble.
13. The aqueous composition of claim 1, wherein the dispersed
core-shell particles comprise cores of organic solids and shells of
polymers that contain in copolymerized form at least one monomer
(A) and at least one monomer (B).
14. The aqueous primary composition of claim 1, wherein the cores
of the core-shell particles are prepared by one of free-radical
microemulsion polymerization and miniemulsion free-radical
polymerization.
15. The aqueous composition of claim 1, wherein the composition
further comprises at least one coatings additive.
16. The aqueous composition of claim 1, wherein the composition
further comprises a constituent that can be cured with actinic
radiation.
17. A process for preparing the aqueous composition of claim 1
comprising controlled free-radical microemulsion or miniemulsion
polymerizing monomer (A) and monomer (B) in the presence of at
least one hydrophobic crosslinking agent (C) for the polymerization
product of (A) and (B).
18. The process of claim 17, wherein the aryl radical is one of a
phenyl radical and a naphthyl radical.
19. The process of claim 17, wherein the substituent in at least
one of R.sup.1, R.sup.2, R.sup.3, and R.sup.4 is one of an
electron-withdrawing atom, an electron-donating atom, and an
organic radical.
20. The process of claim 19, wherein the substituent is at least
one of a halogen atom, a nitrile, a nitro group, an at least
partially halogenated alkyl radical, an at least partially
halogenated cycloalkyl radical, an at least partially halogenated
alkylcycloalkyl radical, an at least partially halogenated
cycloalkylalkyl radical, an at least partially halogenated aryl
radical, an at least partially halogenated alkylaryl radical, an at
least partially halogenated cycloalkylaryl radical, an at least
partially halogenated arylalkyl radical, and an at least partially
halogenated arylcycloalkyl radical, an aryloxy radical, a alkyloxy
radical, and a cycloalkyloxy radical, an arylthio radical, a
alkylthio radical, a cycloalkylthio radical, a primary amino group,
a secondary amino group, and a tertiary amino group.
21. The process of claim 17, wherein the crosslinking agent is at
least one of a blocked polyisocyanate, a
tris(alkoxycarbonylamino)triazine, and a fully etherified amino
resin.
22. The process of claim 17, wherein the monomers (A) and (B) are
copolymerized in the presence of at least one further hydrophobic
compound (D) other than the crosslinking agent (C).
23. The process of claim 22, wherein the further hydrophobic
compound is water-insoluble and is one of a polymer, an oligomer,
and a substances of low molecular mass.
24. The process of claim 23, wherein the further hydrophobic
compound is at least one of: i) an ester of an
.alpha.,.beta.-monoolefinically unsaturated carboxylic acid, having
3 to 6 carbon atoms, with an alcohol having 12 to 30 carbon atoms
in the alkyl radical; ii) an ester of a) at least one of a vinyl
alcohol and an allyl alcohol with b) at least one of an
alkanemonocarboxylic acid, an alkanemonosulfonic acid, and an
alkanemonophosphonic acid having 12 to 30 carbon atoms in the
molecule; iii) an amide of an .alpha.,.beta.-monoolefinically
unsaturated carboxylic acid having 3 to 6 carbon atoms with an
alkylamine having 12 to 30 carbon atoms in the alkyl radical; iv) a
macromonomer comprising an olefinically unsaturated compound having
on average at least one olefinically unsaturated group in the
molecule; v) a polysiloxane macromonomer having on average at least
one olefinically unsaturated group in the molecule; vi) at least
one of an oligomeric reaction product and a polymeric reaction
product of at least one of addition polymerization,
polycondensation, and polyaddition; vii) a water-insoluble
molecular weight regulator; viii) at least one of an alkanol and an
alkylamine having at least 12 carbon atoms in the alkyl radical;
ix) at least one of an organosilane and an organosiloxane; x) at
least one of a vegetable oil, an animal oil, a semisynthetic oil,
and a synthetic oil; and xi) a hydrophobic dye.
25. The process of claim 17, wherein the monomers (A) and (B) are
copolymerized in the presence of at least one of an emulsifier and
a protective colloid.
26. The process of claim 17, wherein monomer (A) is at least one
of: a1) a (meth)acrylic ester; a2) a monomer that carries per
molecule at least one hydroxyl group; a3) a monomer that carries
per molecule at least one acid group that can be converted into a
corresponding acid anion group; a4) a vinyl ester of an
alpha-branched monocarboxylic acid having 5 to 18 carbon atoms in
the molecule; a5) a reaction product of a (meth)acrylic acid with a
glycidyl ester of an alpha-branched monocarboxylic acid having from
5 to 18 carbon atoms per molecule; a6) at least one of a cyclic
olefin and an acyclic olefin; a7) a (meth)acrylamide; a8) a monomer
containing at least one epoxide group; a9) a vinylaromatic
hydrocarbon; a10) a nitrile; a11) a vinyl compound; a12) an allyl
compound; a13) a polysiloxane macromonomer having a number-average
molecular weight Mn of from 1,000 to 40,000 and containing on
average from 0.5 to 2.5 ethylenically unsaturated double bonds per
molecule; and a14) an acryloyloxysilane-containing vinyl monomer
comprising a reaction product of a material and at least one of
methacrylic acid and a hydroxyalkyl ester of (meth)acrylic acid,
wherein the material comprises a reaction product of a
hydroxy-functional silane and epichlorohydrin; with the proviso
that the monomer (a3) is not used as the sole monomer (A).
27. The process of claim 17, wherein at least one monomer (A)
contains reactive functional groups that are able to undergo a
crosslinking reaction with a complementary reactive functional
group of the crosslinking agent (C).
28. The process of claim 17, wherein the controlled free-radical
microemulsion or miniemulsion polymerization is initiated by an
initiator that forms free radicals and is at least one of
water-soluble and oil-soluble.
29. The process of claim 17, wherein the dispersed core-shell
particles comprise cores of organic solids and shells of polymers
that contain in copolymerized form at least one monomer (A) and at
least one monomer (B).
30. The process composition of claim 17, wherein the cores of the
core-shell particles are prepared by one of free-radical
microemulsion polymerization and miniemulsion free-radical
polymerization.
31. The process of claim 17 further comprising adding at least one
of a crosslinking agent, an additional binder, a coatings additive,
and an additive that can be cured with actinic radiation.
32. The process of claim 17 further comprising applying the aqueous
composition to a substrate to provide one of an automotive OEM
finish, an automotive refinish, an industrial coating, a coil
coating, a container coating, an electrical component coating, and
a furniture coating.
33. The process of claim 17 further comprising forming at least one
coat on a substrate, wherein the substrate is one of primed and
unprimed, and wherein the coat is at least one of a clearcoat, a
color paint system, an effect paint system, and a color and effect
paint system.
34. The substrate formed by the process of claim 33.
Description
This application is a National Phase Application of PCT/EP00/11006
filed on 8 Nov. 2000.
The present invention relates to novel aqueous primary dispersions
and coating materials which comprise dispersed and/or emulsified,
solid and/or liquid polymer particles and/or dispersed solid
core-shell particles having a diameter.ltoreq.500 nm. The present
invention further relates to a novel process for preparing the
novel aqueous primary dispersions and coating materials by means of
controlled free-radical microemulsion and miniemulsion
polymerization. The present invention relates, furthermore, to the
use of the novel aqueous primary dispersions and coating materials
for producing single-coat or multicoat clearcoat systems and
single-coat or multicoat color and/or effect paint systems in
automotive OEM finishing and refinishing, industrial coating,
including container coating, coil coating and the coating of
electrical components, and furniture coating.
Microemulsions and miniemulsions are dispersions comprising water,
an oil phase and one or more surface-active substances and having
droplet sizes of from 5 to 50 nm (microemulsions) or from 50 to 500
nm.
Microemulsions are regarded as being thermodynamically stable,
whereas the miniemulsions are regarded as metastable (cf. Emulsion
Polymerization and Emulsion Polymers, Editors: P. A. Lovell and
Mohamed S. El-Aasser, John Wiley and Sons, Chichester, N.Y.,
Weinheim, 1997, pages 700 et seq.; Mohamed S. El-Aasser, Advances
in Emulsion Polymerization and Latex Technology, 30th Annual Short
Course, Volume 3, Jun. 7-11, 1999, Emulsion Polymers Institute,
Lehigh University, Bethlehem, Pa., USA). Both types of dispersions
find broad application in the art: for example, in cleaning
products, cosmetics or bodycare products. They may, however, also
be used for polymerization reactions in place of the customary
macroemulsions, in which droplet sizes>1000 nm are present.
It would be desirable here to carry out the free-radical
polymerization in microemulsion and miniemulsion by the so-called
batch procedure, where the total amount of the monomers is
introduced as initial charge in an aqueous medium, emulsified and
subsequently polymerized to completion. This would make it possible
to avoid from the outset the problems which result from the feed
technique. These problems consist in particular in a comparatively
high level of expenditure on measurement and control equipment and
on apparatus, and in the fact that the monomers being fed in do not
arrive at the site of polymerization but instead, as with
macroemulsion polymerization, serve as a monomer reservoir for the
initiated monomer droplets. As a result, these droplets change
their composition continuously, which in the case of their
subsequent initiation can lead to nonuniformity in the composition
of the resultant polymer particles.
The preparation of aqueous primary dispersions by means of
free-radical miniemulsion polymerization is known, for example,
from the international patent application WO 98/02466 or from
German patents DE-A-196 28 143 and DE-A-196 28 142. In the case of
these known processes, the monomers may be copolymerized in the
presence of different low molecular mass, oligomeric or polymeric,
hydrophobic substances. Furthermore, hydrophobic, organic
auxiliaries of low solubility in water, such as plasticizers,
enhancers of the tackiness of the resulting film, film-forming
auxiliaries or other, unspecified organic additives, may be
incorporated into the monomer droplets of the miniemulsion. The use
of diphenylethylene as a comonomer and of hydrophobic crosslinking
agents for the copolymers formed from the monomers, and the use of
the known aqueous primary dispersions for preparing coating
materials, are equally not evident from the abovementioned patents.
Although the known processes solve the problem of the exothermic
nature of the free-radical polymerization and copolymerization to a
certain extent, they do so at the expense of an increased level of
measurement and control equipment.
Aqueous coating materials based on aqueous primary dispersions
which comprise solid core-shell particles and have been prepared by
miniemulsion polymerization of monomers in the presence of
hydrophobic polymers are known from the patents EP-A-0 401 565, WO
97/49739 or EP-A-0 755 946. The use of a diphenylethylene comonomer
and copolymerization in the presence of hydrophobic crosslinking
agents for the copolymers formed from the monomers are not
disclosed by these patents. Although the known coating materials
already have numerous advantageous properties, there is still the
occurrence of problems associated with inadequate distribution of
the crosslinking agents in the aqueous dispersions. One particular
consequence of this is that a larger amount of crosslinking agents
has to be used than would be theoretically necessary. Unreacted
crosslinking agents may then, in certain circumstances, be harmful
to the performance properties of the coatings produced from the
coating materials.
The microencapsulation of hydrophobic organic solvents or of target
materials such as biocides and herbicides in water-insoluble
core-shell particles produced by miniemulsion polymerization is
known from the patents EP-A-0 203 724 or U.S. Pat. No. 4,677,003.
However, copolymerization is not conducted in the presence of
hydrophobic crosslinking agents for the copolymers formed from the
monomers. Nor is the use of a diphenylethylene comonomer
described.
The patents EP-A-0 622 389 or DE-A-43 14 297 disclose the
copolymerization of monomers in the presence of blocked
polyisocyanates and epoxy resins. However, the technique employed
is not that of miniemulsion polymerization. A comparable process,
but in which the crosslinking agents are not specified, is
disclosed by the patents EP-A-0 758 347 or WO 95/29944. The
corresponding known copolymers and their primary dispersions are
used for preparing coating materials. The known coating materials
likewise have the problems associated with insufficiently fine
distribution of the crosslinking agents in the coating
materials.
The free-radical addition polymerization employed to prepare
acrylate copolymers is frequently very exothermic and difficult to
control. What this means for the reaction regime is that high
concentrations of monomers and/or the so-called batch procedure,
where the total amount of the monomers is introduced as initial
charge in an aqueous medium, emulsified and subsequently
polymerized to completion, must be avoided. In addition, the
targeted establishment of defined molecular weights, molecular
weight distributions and other properties often causes
difficulties. The targeted establishment of a defined profile of
properties in acrylate copolymers is, however, of great importance
for their use as binders in coating materials, especially aqueous
coating materials, since by this means it is possible to exert
direct influence on the performance properties profile of the
coating materials.
There has therefore been no lack of attempts to regulate the
free-radical copolymerization of olefinically unsaturated monomers
in a targeted way.
For instance, the international patent application WO 98/01478
describes a process in which the copolymerization is conducted in
the presence of a free-radical initiator and of a thiocarbonylthio
compound as chain transfer agent.
The international patent application WO 92/13903 describes a
process for preparing copolymers of low molecular weight by
free-radical chain polymerization in the presence of a group
transfer agent having a carbon-sulfur double bond. These compounds
act not only as chain transfer agents but also as growth
regulators, and so result only in copolymers of low molecular
weight.
The international patent application WO 96/15157 discloses a
process for preparing copolymers having a comparatively narrow
molecular weight distribution, in which a monomer is reacted with a
vinyl-terminated macromonomer in the presence of a free-radical
initiator.
Furthermore, the international patent application WO 98/37104
discloses the preparation of acrylate copolymers having defined
molecular weights by free-radical polymerization in the presence of
a chain transfer agent having a C--C double bond and having
radicals which activate this double bond in respect of the
free-radical addition of monomers.
Despite significant progress in this field, there continues to be a
lack of a universally applicable process of controlled free-radical
polymerization which yields chemically structured polymers,
especially acrylate copolymers, in a simple manner and by means of
which it is possible to tailor the profile of properties of the
polymers in respect of their application in coating materials,
especially aqueous coating materials, which are used to produce
clearcoats and multicoat color and/or effect paint systems.
It is an object of the present invention to find new aqueous
primary dispersions and coating materials comprising dispersed
and/or emulsified, solid and/or liquid polymer particles and/or
dispersed solid core-shell particles having a diameter.ltoreq.500
nm which no longer have the disadvantages of the prior art but
instead can be prepared in a simple and controlled manner. The
copolymers present in the new aqueous primary dispersions and
coating materials ought to have defined molecular weights and ought
to be preparable inter alia by the batch procedure without the
occurrence in this case of the problems associated with the highly
exothermic nature of the free-radical polymerization, ranging for
instance from the thermal damaging of the products through to
runaway of the reactor. Moreover, the new aqueous primary
dispersions and coating materials ought to contain very finely
distributed crosslinking agents.
A further object of the present invention was to find a new process
for preparing aqueous primary dispersions and coating materials by
free-radical microemulsion or miniemulsion polymerization which no
longer has the disadvantages of the prior art, but can instead be
carried out by the batch procedure without the problems described
above occurring, and which allows the profile of properties of the
resulting copolymers to be adjusted in a targeted way, especially
in terms of the molecular weight and molecular weight
distribution.
Accordingly, we have found the novel aqueous primary dispersions
and coating materials comprising dispersed and/or emulsified, solid
and/or liquid polymer particles and/or dispersed solid core-shell
particles having a diameter.ltoreq.500 nm, preparable by controlled
free-radical microemulsion or miniemulsion polymerization of A) at
least one olefinically unsaturated monomer and B) at least one
olefinically unsaturated monomer which is different than the
olefinically unsaturated monomer (A) and has the general formula
I
in which the radicals R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each
independently of one another are hydrogen atoms or substituted or
unsubstituted alkyl, cycloalkyl, alkylcycloalkyl, cycloalkylalkyl,
aryl, alkylaryl, cycloalkylaryl arylalkyl or arylcycloalkyl
radicals, with the proviso that at least two of the variables
R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are substituted or
unsubstituted aryl, arylalkyl or arylcycloalkyl radicals,
especially substituted or unsubstituted aryl radicals;
in the presence of at least C) at least one hydrophobic
crosslinking agent for the copolymer resulting from the starting
products (A) and (B),
which are referred to below for short as "primary dispersions of
the invention" and, respectively, "coating materials of the
invention".
We have also found the novel process for preparing aqueous primary
dispersions and coating materials comprising dispersed and/or
emulsified, solid and/or liquid polymer particles and/or dispersed
solid core-shell particles having a diameter.ltoreq.500 nm by
controlled free-radical microemulsion or miniemulsion
polymerization of A) at least one olefinically unsaturated monomer
and B) at least one olefinically unsaturated monomer which is
different than the olefinically unsaturated monomer (A) and has the
general formula I
in which the radicals R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each
independently of one another are hydrogen atoms or substituted or
unsubstituted alkyl, cycloalkyl, alkylcycloalkyl, cycloalkylalkyl,
aryl, alkylaryl, cycloalkylaryl arylalkyl or arylcycloalkyl
radicals, with the proviso that at least two of the variables
R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are substituted or
unsubstituted aryl, arylalkyl or arylcycloalkyl radicals,
especially substituted or unsubstituted aryl radicals;
in the presence of at least C) at least one hydrophobic
crosslinking agent for the copolymer resulting from the starting
products (A) and (B),
which is referred to for short below as "process of the
invention".
Further subjects of the invention will emerge from the following
description.
In the light of the prior art it was surprising and unforeseeable
by the skilled worker that the object on which the present
invention was based could be achieved through the primary
dispersions of the invention and the coating materials of the
invention and also through the process of the invention. In
particular, it was surprising that the copolymers present in the
primary dispersions of the invention had properties which make them
highly suitable for use in coating materials. It was also
surprising that the primary dispersions of the invention can be
used directly as coating materials, even needing less crosslinking
agent than conventional coating materials. Not least, it was
surprising that the process of the invention yields the primary
dispersions and coating materials of the invention in a
particularly simple and targeted manner without the occurrence of
the above-described problems known from the prior art.
For the purposes of the present invention, the property of being
hydrophilic is understood as the constitutional property of a
molecule or functional group to penetrate into the aqueous phase or
to remain therein. Accordingly, for the purposes of the present
invention, the property of being hydrophobic is understood as the
constitutional property of a molecule or functional group to
exhibit exophilic behavior with respect to water; i.e., they
display the tendency not to penetrate into water, or to depart the
aqueous phase. For further details, reference is made to Rompp
Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart,
N.Y., 1998, "Hydrophilicity", "Hydrophobicity", pages 294 and
295.
In accordance with the invention, the primary dispersions and
coating materials comprise dispersed and/or emulsified solid and/or
liquid polymer particles and/or dispersed solid core-shell
particles. The size of the polymer particles or of the dispersed
core-shell particles is a direct result of the process of the
invention described below. In this case the average particle
diameter is less than 500 nm. It is preferably from 10 to 500 nm,
more preferably from 50 to 400 nm, and with very particular
preference from 100 to 350 nm.
The primary dispersions and coating materials of the invention have
an advantageously high solids content of, for example, more than
20% by weight, preferably more than 30% by weight. It is even
possible to obtain solids contents of more than 40% by weight. The
primary dispersions and coating materials of the invention have a
low viscosity, even at high solids content.
The core-shell particles for use in accordance with the invention
result from the graft copolymerization of organic solids and the
comonomers (A) and (B) for use in accordance with the invention,
described below. Said organic solids are preferably hydrophobic
polymers, as described, for example, in the patents EP-A-0 401 565,
page 3, line 5 to page 4, line 50, WO 97/49739, page 4, line 19 to
page 5, line 3, or EP-A-0 755 946, page 3, line 26 to page 5, line
38. These hydrophobic polymers may also be prepared by the process
of the invention.
The primary dispersions and coating materials of the invention may
also have a bimodal particle size distribution in which from 0.1 to
80% by weight, in particular from 1.0 to 50% by weight, of the
copolymer resulting from the comonomers (A) and (B) have a particle
size, determined using an analytical ultracentrifuge, of from 20 to
500 nm, in particular from 50 to 300 nm, and from 20 to 99.9% by
weight, in particular from 50 to 99% by weight, of the copolymer
have a particle size of from 200 to 1500 nm, in particular from 300
to 900 nm, said particle sizes differing by at least 50 nm, in
particular by at least 100 nm, with very particular preference by
at least 200 nm. Concerning the measurement method, reference is
made for further details to lines 5 to 9 of page 6 of the German
patent application DE-A-196 28 142.
The first starting compound essential to the invention for the
primary dispersions or coating materials of the invention, and for
the process of the invention, is at least one olefinically
unsaturated monomer (A).
It is preferred here to use at least one monomer (A) comprising
reactive functional groups which are able to enter into
crosslinking reactions with the complementary reactive functional
groups of the crosslinking agents (C). Examples of suitable
complementary reactive functional groups for use in accordance with
the invention are collated in the overview below. In the overview,
the variable R is an acyclic or cyclic aliphatic radical, an
aromatic radical and/or an aromatic-aliphatic (araliphatic)
radical; the variables R' and R" are identical or different
aliphatic radicals or are linked to one another to form an
aliphatic or heteroaliphatic ring.
Overview: Examples of Complementary Functional Groups
Monomer (A) and crosslinking agent (C) or Crosslinking agent (C)
and monomer (A) --SH --C(O)--OH --NH.sub.2 --C(O)--O--C(O)-- --OH
--NCO --O--(CO)--NH--(CO)--NH.sub.2 --NH--C(O)--OR
--O--(CO)--NH.sub.2 --CH.sub.2 --OH >NH --CH.sub.2 --O--CH.sub.3
--NH--C(O)--CH(--C(O)- OR).sub.2 --NH--C(O)--CH(--C(O)-
OR)(--C(O)--R) --NH--C(O) --NR'R" =Si(OR).sub.2 ##STR1## --C(O)--OH
##STR2##
The selection of the respective complementary groups is guided on
the one hand by the consideration that, during the storage of
primary dispersions or coating materials of the invention, these
groups do not enter into any unwanted reactions and/or, if
appropriate, do not inhibit or disrupt curing with actinic
radiation, and on the other hand by the temperature range within
which crosslinking is to take place.
For the coating materials of the invention it is preferred to
employ crosslinking temperatures of from 100.degree. C. to
180.degree. C. It is therefore preferred to use monomers (A)
containing thio, hydroxyl, alkoxymethylamino, imino, carbamate,
allophanate and/or carboxyl groups, but in particular amino,
alkoxymethylamino or hydroxyl groups, especially hydroxyl groups,
on the one hand, and crosslinking agents (C) containing anhydride,
carboxyl, epoxy, blocked isocyanate, urethane, methylol, methylol
ether, siloxane, amino, hydroxyl and/or beta-hydroxyalkylamide
groups, but especially blocked isocyanate, urethane or methylol
ether groups, on the other.
Examples of Suitable Monomers (A) are a1) substantially
acid-group-free (meth)acrylic esters such as (meth)acrylic alkyl or
cycloalkyl esters having up to 20 carbon atoms in the alkyl
radical, especially methyl, ethyl, propyl, n-butyl, sec-butyl,
tert-butyl, hexyl, ethylhexyl, stearyl and lauryl acrylate or
methacrylate; cycloaliphatic (meth)acrylic esters, especially
cyclohexyl, isobornyl, dicyclopentadienyl,
octahydro-4,7-methano-1H-indenemethanol (meth)acrylate or
tert-butylcyclohexyl (meth)acrylate; (meth)acrylic oxaalkyl esters
or oxacycloalkyl esters such as ethyltriglycol (meth)acrylate and
methoxyoligoglycol (meth)acrylate having a molecular weight Mn of
preferably 550, or other ethoxylated and/or propoxylated
hydroxyl-free (meth)acrylic acid derivatives. These may contain
minor amounts of (meth)acrylic alkyl or cycloalkyl esters of higher
functionality, such as the di(meth)acrylates of ethylene glycol,
propylene glycol, diethylene glycol, dipropylene glycol, butylene
glycol, 1,5-pentanediol, 1,6-hexanediol,
octahydro-4,7-methano-1H-indenedimethanol or 1,2-, 1,3- or
1,4-cyclohexanediol; trimethylolpropane di- or tri(meth)acrylate;
or pentaerythritol di-, tri- or tetra(meth)acrylate. For the
purposes of the present invention, minor amounts of monomers of
higher functionality in this case are to be understood as amounts
which do not lead to crosslinking or gelling of the copolymers (A).
a2) Monomers which carry per molecule at least one hydroxyl, amino,
alkoxymethylamino or imino group and are substantially free from
acid groups, such as hydroxyalkyl esters of acrylic acid,
methacrylic acid or another alpha,beta-olefinically unsaturated
carboxylic acid, which derive from an alkylene glycol esterified
with the acid, or which are obtainable by reacting the
alpha,beta-olefinically unsaturated carboxylic acid with an
alkylene oxide, especially hydroxyalkyl esters of acrylic acid,
methacrylic acid, ethacrylic acid, crotonic acid, maleic acid,
fumaric acid or itaconic acid in which the hydroxyalkyl group
contains up to 20 carbon atoms, such as 2-hydroxyethyl,
2-hydroxypropyl, 3-hydroxypropyl, 3-hydroxybutyl, 4-hydroxybutyl
acrylate, methacrylate, ethacrylate, crotonate, maleate, fumarate
or itaconate; or hydroxycycloalkyl esters such as
1,4-bis(hydroxymethyl)cyclohexane,
octahydro-4,7-methano-1H-indenedimethanol or methylpropanediol
monoacrylate, monomethacrylate, monoethacrylate, monocrotonate,
monomaleate, monofumarate or monoitaconate; or reaction products of
cyclic esters, such as epsilon-caprolactone, for example, and these
hydroxyalkyl or hydroxycycloalkyl esters; or olefinically
unsaturated alcohols such as allyl alcohol or polyols such as
trimethylolpropane monoallyl or diallyl ether or pentaerythritol
monoallyl, diallyl or triallyl ether (as far as these monomers (a2)
of higher functionality are concerned, the comments made above
relating to the monomers (a1) of higher functionality apply
analogously); N,N-dimethylaminoethyl acrylate,
N,N-diethylaminoethyl methacrylate, allylamine or
N-methyliminoethyl acrylate or N,N-di(methoxymethyl)aminoethyl
acrylate and methacrylate or N,N-di(butoxymethyl)aminopropyl
acrylate and methacrylate; a3) monomers which carry per molecule at
least one acid group which can be converted into the corresponding
acid anion group, such as acrylic acid, methacrylic acid,
ethacrylic acid, crotonic acid, maleic acid, fumaric acid or
itaconic acid; olefinically unsaturated sulfonic or phosphonic
acids or their partial esters; or mono(meth)acryloyloxyethyl
maleate, succinate or phthalate. For the purposes of the present
invention the monomers (a3) are not used as the sole monomers (A)
but are always used in conjunction with other monomers (A) and,
moreover, in amounts so small that the monomers (a3) do not
polymerize outside the droplets of the miniemulsion. a4) Vinyl
esters of alpha-branched monocarboxylic acids having 5 to 18 carbon
atoms in the molecule. The branched monocarboxylic acids can be
obtained by reacting formic acid or carbon monoxide and water with
olefins in the presence of a liquid, strongly acidic catalyst; the
olefins may be cracking products of paraffinic hydrocarbons, such
as mineral oil fractions, and may comprise both branched and
straight-chain acyclic and/or cycloaliphatic olefins. The reaction
of such olefins with formic acid or, respectively, with carbon
monoxide and water produces a mixture of carboxylic acids in which
the carboxyl groups are located predominantly on a quaternary
carbon atom. Examples of other olefinic starting materials are
propylene trimer, propylene tetramer and diisobutylene.
Alternatively, the vinyl esters (a4) may be prepared in
conventional manner from the acids, by reacting, for example, the
acid with acetylene. Particular preference, owing to their ready
availability, is given to using vinyl esters of saturated aliphatic
monocarboxylic acids having 9 to 11 carbon atoms that are branched
on the alpha carbon atom, but especially Versatic.RTM. acids. a5)
Reaction products of acrylic acid and/or methacrylic acid with the
glycidyl ester of an alpha-branched monocarboxylic acid having from
5 to 18 carbon atoms per molecule, in particular a Versatic.RTM.
acid, or, instead of the reaction product, an equivalent amount of
acrylic and/or methacrylic acid which is then reacted during or
after the polymerization reaction with the glycidyl ester of an
alpha-branched monocarboxylic acid having 5 to 18 carbon atoms per
molecule, especially a Versatic.RTM. acid. a6) Cyclic and/or
acyclic olefins such as ethylene, propylene, 1-butene, 1-pentene,
1-hexene, cyclohexene, cyclopentene, norbornene, butadiene,
isoprene, cyclopentadiene and/or dicyclopentadiene. a7)
(Meth)acrylamides such as (meth)acrylamide, N-methyl-,
N,N-dimethyl-, N-ethyl-, N,N-diethyl-, N-propyl-, N,N-dipropyl-,
N-butyl-, N,N-dibutyl-, N-cyclohexyl-, N,N-cyclohexylmethyl- and/or
N-methylol-, N,N-dimethylol-, N-methoxymethyl-,
N,N-di(methoxymethyl)-, N-ethoxymethyl- and/or
N,N-di(ethoxyethyl)-(meth)acrylamide; a8) monomers containing
epoxide groups, such as the glycidyl ester of acrylic acid,
methacrylic acid, ethacrylic acid, crotonic acid, maleic acid,
fumaric acid and/or itaconic acid. a9) Vinylaromatic hydrocarbons
such as styrene, alpha-alkylstyrenes, especially
alpha-methylstyrene, and/or vinyltoluene; vinylbenzoic acid (all
isomers), N,N-diethylaminostyrene (all isomers),
alpha-methylvinylbenzoic acid (all isomers),
N,N-diethylamino-alpha-methylstyrene (all isomers) and/or
p-vinylbenzenesulfonic acid. a10) Nitriles such as acrylonitrile
and/or methacrylonitrile. a11) Vinyl compounds, especially vinyl
halides and/or vinylidene dihalides such as vinyl chloride, vinyl
fluoride, vinylidene dichloride or vinylidene difluoride;
N-vinylamides such as vinyl-N-methylformamide, N-vinylcaprolactam,
1-vinylimidazole or N-vinylpyrrolidone; vinyl ethers such as ethyl
vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl
vinyl ether, isobutyl vinyl ether and/or vinyl cyclohexyl ether;
and/or vinyl esters such as vinyl acetate, vinyl propionate, vinyl
butyrate, vinyl pivalate and/or the vinyl ester of
2-methyl-2-ethylheptanoic acid. a12) Allyl compounds, especially
allyl ethers and allyl esters such as allyl methyl, ethyl, propyl
or butyl ether or allyl acetate, propionate or butyrate. a13)
Polysiloxane macromonomers having a number-average molecular weight
Mn of from 1000 to 40,000 and having on average from 0.5 to 2.5
ethylenically unsaturated double bonds per molecule; especially
polysiloxane macromonomers having a number-average molecular weight
Mn of from 2000 to 20,000, with particular preference from 2500 to
10,000 and, in particular, from 3000 to 7000 and having on average
from 0.5 to 2.5, preferably from 0.5 to 1.5, ethylenically
unsaturated double bonds per molecule, as are described in DE-A-38
07 571 on pages 5 to 7, in DE-A-37 06 095 in columns 3 to 7, in
EP-B-0 358 153 on pages 3 to 6, in U.S. Pat. No. 4,754,014 in
columns 5 to 9, in DE-A-44 201 823 or in the international patent
application WO 92/22615 on page 12, line 18 to page 18, line
10.
and/or a14) Acryloyloxysilane-containing vinyl monomers, preparable
by reacting hydroxy-functional silanes with epichlorohydrin and
then reacting the reaction product with (meth)acrylic acid and/or
hydroxyalkyl and/or hydroxycycloalkyl esters of (meth)acrylic acid
(cf. monomers a2).
Each of the abovementioned monomers (a1) to (a14), with the
exception of the monomer (a3), can be polymerized alone with the
monomers (B). In accordance with the invention, however, it is
advantageous to use at least two monomers (A), since by this means
it is possible to vary the profile of properties of the resulting
copolymers very widely, in a particularly advantageous manner, and
to tailor said profile of properties very targetedly to the
particular intended use of the primary dispersions of the invention
or of the coating materials of the invention.
Further examples of suitable monomers (A) are disclosed in the
German patent application DE-A-196 28 142, page 2, line 5 to page
3, line 7.
Preferably, the monomers (A) are selected so as to give
(meth)acrylate copolymers whose profile of properties is determined
primarily by the (meth)acrylates described above. In that case it
is preferred as comonomer (A) to use vinylaromatic hydrocarbons
(a9); especially styrene.
The second starting products, essential to the invention, for
preparing the primary dispersions and coating materials of the
invention and for the process of the invention is at least one
olefinically unsaturated monomer (B) which is different than the
above-described monomers (A).
The olefinically unsaturated monomer (B) for use in accordance with
the invention has the general formula I
In the general formula I, the radicals R.sup.1, R.sup.2, R.sup.3
and R.sup.4 each independently of one another are hydrogen atoms or
substituted or unsubstituted alkyl, cycloalkyl, alkylcycloalkyl,
cycloalkylalkyl, aryl, alkylaryl, cycloalkylaryl arylalkyl or
arylcycloalkyl radicals, with the proviso that at least two of the
variables R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are substituted or
unsubstituted aryl, arylalkyl or arylcycloalkyl radicals,
especially substituted or unsubstituted aryl radicals.
Examples of suitable alkyl radicals are methyl, ethyl, propyl,
isopropyl, n-butyl, isobutyl, tert-butyl, amyl, hexyl or
2-ethylhexyl.
Examples of suitable cycloalkyl radicals are cyclobutyl,
cyclopentyl or cyclohexyl.
Examples of suitable alkylcycloalkyl radicals are
methylenecyclohexane, ethylenecyclohexane or
propane-1,3-diylcyclohexane.
Examples of suitable cycloalkylalkyl radicals are 2-, 3- or
4-methyl-, -ethyl-, -propyl- or -butylcyclohex-1-yl.
Examples of suitable aryl radicals are phenyl, naphthyl or
biphenylyl, preferably phenyl and naphthyl, and especially
phenyl.
Examples of suitable alkylaryl radicals are benzyl or ethylene- or
propane-1,3-diylbenzene.
Examples of suitable cycloalkylaryl radicals are 2-, 3- or
4-phenylcyclohex-1-yl.
Examples of suitable arylalkyl radicals are 2-, 3- or 4-methyl-,
-ethyl-, -propyl- or -butylphen-1-yl.
Examples of suitable arylcycloalkyl radicals are 2-, 3- or
4-cyclohexylphen-1-yl.
The above-described radicals R.sup.1, R.sup.2, R.sup.3 and R.sup.4
may be substituted. For this purpose it is possible to use
electron-withdrawing or electron-donating atoms or organic
radicals.
Examples of suitable substituents are halogen atoms, especially
chorine and fluorine, nitrile groups, nitro groups, partially or
fully halogenated, especially chlorinated and/or fluorinated,
alkyl, cycloalkyl, alkylcycloalkyl, cycloalkylalkyl, aryl,
alkylaryl, cycloalkylaryl arylalkyl and arylcycloalkyl radicals,
including those exemplified above, especially tert-butyl; aryloxy,
alkyloxy and cycloalkyloxy radicals, especially phenoxy, naphthoxy,
methoxy, ethoxy, propoxy, butyloxy or cyclohexyloxy; arylthio,
alkylthio and cycloalkylthio radicals, especially phenylthio,
naphthylthio, methylthio, ethylthio, propylthio, butylthio or
cyclohexylthio; hydroxyl groups; and/or primary, secondary and/or
tertiary amino groups, especially amino, N-methylamino,
N-ethylamino, N-propylamino, N-phenylamino, N-cyclohexylamino,
N,N-dimethylamino, N,N-diethylamino, N,N-dipropylamino,
N,N-diphenylamino, N,N-dicyclohexylamino,
N-cyclohexyl-N-methylamino or N-ethyl-N-methylamino.
Examples of monomers (B) used with particular preference in
accordance with the invention are diphenylethylene,
dinaphthaleneethylene, cis- or trans-stilbene,
vinylidenebis(4-N,N-dimethylaminobenzene),
vinylidenebis(4-aminobenzene) or vinylidenebis(4-nitrobenzene).
In accordance with the invention, the monomers (B) may be used
individually or as a mixture of at least two monomers (B).
The proportion of the monomers (B) in the monomer mixture (A) and
(B), based in each case on the mixture, is preferably from 0.01 to
10%, more preferably from 0.1 to 9.0%, with particular preference
from 0.15 to 8.0%, with very particular preference from 0.2 to
7.0%, and in particular from 0.25 to 6.0% by weight.
As regards the reaction regime and the properties of the resulting
copolymers, especially the acrylate copolymers, diphenylethylene is
of very particular advantage and is therefore used with very
particular preference in accordance with the invention.
The monomers (A) and (B) to be used in accordance with the
invention are reacted with one another to form copolymers in the
presence of at least one water-soluble and/or oil-soluble initiator
which forms free radicals. Examples of initiators which can be used
are: dialkyl peroxides, such as di-tert-butyl peroxide or dicumyl
peroxide; hydroperoxides, such as cumene hydroperoxide or
tert-butyl hydroperoxide; peresters, such as tert-butyl
perbenzoate, tert-butyl perpivalate, tert-butyl
per-3,5,5-trimethylhexanoate or tert-butyl per-2-ethylhexanoate;
peroxodicarbonates; potassium, sodium or ammonium peroxodisulfate;
azo initiators, examples being azodinitriles such as
azobisisobutyronitrile; C--C-cleaving initiators such as
benzpinacol silyl ethers; or a combination of a nonoxidizing
initiator with hydrogen peroxide. Further examples of suitable
initiators are described in the German patent application DE-A-196
28 142, page 3, line 49 to page 4, line 6. Combinations of these
initiators may also be used.
It is preferred to add comparatively large amounts of free-radical
initiator, the proportion of the initiator in the reaction mixture
being, based in each case on the overall amount of the monomers (A)
and of the initiator, with particular preference from 0.2 to 20% by
weight, with very particular preference from 0.5 to 15% by weight,
and in particular from 1.0 to 10% by weight.
The weight ratio of initiator to the monomers (B) is preferably
from 5:1 to 1:20.
The monomers (A) and (B) are, in accordance with the invention,
copolymerized in the presence of at least one hydrophobic
crosslinking agent. The hydrophobic crosslinking agents preferably
contain the above-described reactive functional groups which
undergo crosslinking reactions with the complementary reactive
functional groups present in the resultant copolymers.
Examples of especially suitable crosslinking agents (C) are blocked
polyisocyanates, tris(alkoxycarbonylamino)triazines or fully
etherified amino resins.
Examples of suitable blocking agents for preparing the blocked
polyisocyanates (C) are the blocking agents known from the U.S.
patent U.S. Pat. No. 4,444,954: i) phenols such as phenol, cresol,
xylenol, nitrophenol, chlorophenol, ethylphenol, t-butylphenol,
hydroxybenzoic acid, esters of these acids, or
2,5-di-tert-butyl-4-hydroxytoluene; ii) lactams, such as
.epsilon.-caprolactam, .delta.-valerolactam, .gamma.-butyrolactam
or .beta.-propiolactam; iii) active methylenic compounds, such as
diethyl malonate, dimethyl malonate, ethyl or methyl acetoacetate,
or acetylacetone; iv) alcohols such as methanol, ethanol,
n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, n-amyl
alcohol, t-amyl alcohol, lauryl alcohol, ethylene glycol monomethyl
ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl
ether, diethylene glycol monomethyl ether, diethylene glycol
monoethyl ether, propylene glycol monomethyl ether,
methoxymethanol, glycolic acid, glycolic esters, lactic acid,
lactic esters, methylolurea, methylolmelamine, diacetone alcohol,
ethylenechlorohydrin, ethylenebromohydrin, 1,3-dichloro-2-propanol,
1,4-cyclohexyldimethanol or acetocyanohydrin; v) mercaptans such as
butyl mercaptan, hexyl mercaptan, t-butyl mercaptan, t-dodecyl
mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol or
ethylthiophenol; vi) acid amides such as acetoanilide,
acetoanisidine amide, acrylamide, methacrylamide, acetamide,
stearamide or benzamide; vii) imides such as succinimide,
phthalimide or maleimide; viii) amines such as diphenylamine,
phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole,
aniline, naphthylamine, butylamine, dibutylamine or
butylphenylamine; ix) imidazoles such as imidazole or
2-ethylimidazole; x) ureas such as urea, thiourea, ethyleneurea,
ethylenethiourea or 1,3-diphenylurea; xi) carbamates such as phenyl
N-phenylcarbamate or 2-oxazolidone; xii) imines such as
ethyleneimine; xiii) oximes such as acetone oxime, formaldoxime,
acetaldoxime, acetoxime, methyl ethyl ketoxime, diisobutyl
ketoxime, diacetyl monoxime, benzophenone oxime or chlorohexanone
oximes; xiv) salts of sulfurous acid such as sodium bisulfite or
potassium bisulfite; xv) hydroxamic esters such as benzyl
methacrylohydroxamate (BMH) or allyl methacrylohydroxamate; or xvi)
substituted pyrazoles, especially dimethylpyrazole, or triazoles;
and also xvii) mixtures of these blocking agents, especially
dimethylpyrazole and triazoles, malonic esters and acetoacetic
esters or dimethylpyrazole and succinimide.
Examples of suitable organic polyisocyanates for blocking are in
particular the so-called paint polyisocyanates having isocyanate
groups attached to aliphatic, cycloaliphatic, araliphatic and/or
aromatic structures. Preference is given to polyisocyanates having
from 2 to 5 isocyanate groups per molecule and having viscosities
of from 100 to 10,000, preferably from 100 to 5000.
Further examples of suitable polyisocyanates for blocking are
described in "Methoden der organischen Chemie", Houben-Weyl, Volume
14/2, 4.sup.th edition, Georg Thieme Verlag, Stuttgart 1963, pages
61 to 70, and by W. Siefken, Liebigs Annalen der Chemie, Volume
562, pages 75 to 136. Examples of those suitable are the
polyurethane prepolymers containing isocyanate groups, which can be
prepared by reacting polyols with an excess of polyisocyanates and
which are preferably of low viscosity.
Further examples of suitable polyisocyanates for blocking are
polyisocyanates containing isocyanurate, biuret, allophanate,
iminooxadiazinedione, urethane, urea and/or uretdione groups.
Polyisocyanates containing urethane groups, for example, are
prepared by reacting some of the isocyanate groups with polyols,
such as trimethylolpropane and glycerol, for example. Preference is
given to the use of aliphatic or cycloaliphatic polyisocyanates,
especially hexamethylene diisocyanate, dimerized and trimerized
hexamethylene diisocyanate isophorone diisocyanate,
dicyclohexyl-methane 2,4'-diisocyanate; dicyclohexylmethane
4,4'-diisocyanate, diisocyanates derived from dimeric fatty acids,
as marketed under the commercial designation DDI 1410 by Henkel and
described in patents WO 97/49745 and WO 97/49747, especially
2-heptyl-3,4-bis(9-isocyanatononyl)-1-pentylcyclohexane; or 1,2-,
1,4- or 1,3-bis(isocyanatomethyl)cyclohexane, 1,2-, 1,4- or
1,3-bis(2-isocyanatoeth-1-yl)cyclohexane,
1,3-bis(3-isocyanatoprop-1-yl)cyclohexane or 1,2-, 1,4- or
1,3-bis(4-isocyanatobut-1-yl)cyclohexane,
1,8-diisocyanato-4-isocyanatomethyloctane,
1,7-diisocyanato-4-isocyanatomethylheptane or
1-isocyanato-2-(3-isocyanatopropyl)cyclohexane, or mixtures of
these polyisocyanates.
Very particular preference is given to the use of mixtures of
polyisocyanates containing uretdione and/or isocyanurate groups
and/or allophanate groups based on hexamethylene diisocyanate, as
are formed by catalytic oligomerization of hexamethylene
diisocyanate using appropriate catalysts.
Examples of particularly highly suitable amino resins (C) are
melamine resins, guanamine resins or urea resins. In this context
it is possible to use any amino resin that is suitable for
clearcoats, or a mixture of such amino resins. For further details
refer to Rompp Lexikon Lacke und Druckfarben, Georg Thieme Verlag,
1998, page 29, "Amino resins", and the textbook "Lackadditive" by
Johan Bieleman, Wiley-VCH, Weinheim, N.Y., 1998, pages 242 ff., or
to the book "Paints, Coatings and Solvents", second completely
revised edition, editors: D. Stoye and W. Freitag, Wiley-VCH,
Weinheim, N.Y., 1998, pages 80 ff. Also suitable are the customary
and known amino resins some of whose methylol and/or methoxymethyl
groups have been defunctionalized by means of carbamate or
allophanate groups. Crosslinking agents of this kind are described
in the patents U.S. Pat. No. 4,710,542 and EP-B-0 245 700 and also
in the article by B. Singh and coworkers "Carbamylmethylated
Melamines, Novel Crosslinkers for the Coatings Industry" in
Advanced Organic Coatings Science and Technology Series, 1991,
Volume 13, pages 193 to 207.
The particularly highly suitable
tris-(alkoxycarbonylamino)triazines had the following formula:
##STR3##
Examples of particularly highly suitable
tris(alkoxycarbonylamino)triazines are described in the patents
U.S. Pat. Nos. 4,939,213, 5,084,541 or EP-A-0 624 577. Use is made
in particular of the tris(methoxy-, tris(butoxy- and/or
tris(2-ethylhexoxycarbonylamino)-triazines.
The methyl butyl mixed esters, the butyl 2-ethylhexyl mixed esters
and the butyl esters are of advantage. They have the advantage over
the simple methyl ester of better solubility in polymer melts and
also have a lower tendency to crystallize out.
Of the crosslinking agents (C) described above, the blocked
polyisocyanates offer particular advantages and are therefore used
with very particular preference in accordance with the
invention.
In the process of the invention, the ratio of the monomers (A)
comprising complementary reactive functional groups to the
crosslinking agents (C) may vary very widely. In accordance with
the invention it is of advantage if the molar ratio of
complementary reactive functional groups in (A) to complementary
reactive functional groups in (C) is from 5.0:1.0 to 1.0:5.0,
preferably from 4.0:1.0 to 1.0:4.0, with particular preference from
3.0:1.0 to 1.0:3.0, and in particular from 2.0:1 to 1:2.0.
Particular advantages result if the molar ratio is approximately or
precisely 1.0:1.0.
In addition to the hydrophobic crosslinking agents (C) for use in
accordance with the invention and described above, the
copolymerization of the monomers (A) and (B) to be used in
accordance with the invention may also be accompanied by
hydrophobic compounds (D) which differ from (C). These hydrophobic
compounds (D) are also referred to by those in the art as
costabilizers.
The hydrophobic compounds (D) comprise water-insoluble polymers,
oligomers or substances of low molecular mass. Examples of suitable
hydrophobic compounds (D) are esters of alpha,beta-monoolefinically
unsaturated carboxylic acids, having 3 to 6 carbon atoms, with
alcohols having 12 to 30 carbon atoms in the alkyl radical; esters
of vinyl alcohol and/or allyl alcohol with alkanemonocarboxylic,
-sulfonic and/or -phosphonic acids having 12 to 30 carbon atoms in
the molecule; amides of alpha,beta-monoolefinically unsaturated
carboxylic acids having 3 to 6 carbon atoms with alkylamines having
12 to 30 carbon atoms in the alkyl radical; macromonomers based on
olefinically unsaturated compounds having on average at least one
olefinically unsaturated group, in particular at least one terminal
olefinically unsaturated group, in the molecule; polysiloxane
macromonomers having on average at least one olefinically
unsaturated group, in particular at least one terminal olefinically
unsaturated group, in the molecule; oligomeric and/or polymeric
products of addition polymerization, polycondensation and/or
polyaddition; water-insoluble molecular weight regulators,
especially mercaptans; aliphatic, cycloaliphatic and/or aromatic
halogenated and/or nonhalogenated hydrocarbons; alkanols and/or
alkylamines having at least 12 carbon atoms in the alkyl radical;
organosilanes and/or organosiloxanes; vegetable, animal,
semisynthetic and/or synthetic oils; hydrophobic dyes. Further
examples of suitable hydrophobic compounds (D) or costabilizers
(D), and the amounts in which they are advantageously used, are
disclosed in the German patent application DE-A-196 28 142, page 4,
lines 37 to 59.
The monomers (A) and (B) for use in accordance with the invention
may further be copolymerized in the presence of emulsifiers and/or
protective colloids (E). Examples of suitable emulsifiers and/or
protective colloids (E), and the amounts in which they are
advantageously used, are disclosed in the German patent application
DE-A-196 28 142, page 3, lines 8 to 48.
In terms of the molecular weight distribution, the copolymer formed
from the comonomers (A) and (B) is not subject to any restrictions
whatsoever. Advantageously, however, the copolymerization is
conducted so as to result in a molecular weight distribution Mw/Mn,
measured by gel permeation chromatography using polystyrene as
standard, of.ltoreq.12, with particular preference.ltoreq.10, and
in particular.ltoreq.7. The molecular weights of the constituents
(A) are controllable within wide ranges by the choice of the ratio
of monomer (A) to monomer (B) to free-radical initiator. In this
relationship, the amount of monomer (B) is a particular determinant
of the molecular weight, specifically such that the higher the
fraction of monomer (B) the lower the molecular weight
obtained.
Suitable reactors for the copolymerization processes are the
customary and known stirred vessels, cascades of stirred vessels,
tube reactors, loop reactors or Taylor reactors, as described, for
example, in the patents DE-B-1 071 241, EP-A-0 498 583 or in the
article by K. Kataoka in Chemical Engineering Science, Volume 50,
No. 9, 1995, pages 1409 to 1416. The free-radical copolymerization
is preferably conducted in stirred vessels or Taylor reactors, the
Taylor reactors being configured such that the conditions of Taylor
flow are met over the entire length of the reactor, even if the
kinematic viscosity of the reaction medium alters greatly--in
particular, increases--as a result of the copolymerization.
In accordance with the invention, the copolymerization is conducted
in an aqueous medium.
The aqueous medium contains essentially water. Besides the
crosslinking agents (C) described in detail above and also any
hydrophobic compounds (D) and/or emulsifiers and/or protective
colloids (E) the aqueous medium may comprise customary and known
coatings additives (F) and/or other dissolved solid, liquid or
gaseous, organic and/or inorganic substances of low and/or high
molecular mass, provided these do not adversely affect, let alone
inhibit, the copolymerization. For the purposes of the present
invention, the term "minor amount" means an amount which does not
destroy the aqueous nature of the aqueous medium.
Alternatively, the aqueous medium may simply consist of water.
The copolymerization is advantageously conducted at temperatures
above room temperature, preference being given to the choice of a
temperature range of from 30 to 95.degree. C., with very particular
preference from 50 to 90.degree. C.
When using particularly volatile monomers (A) and/or (B) the
copolymerization may also be conducted under pressure, preferably
under from 1.5 to 3000 bar, with particular preference from 5 to
1500 and, in particular, from 10 to 1000 bar. In specific cases,
temperatures higher than 95.degree. C. may be used here.
It proves here to be a particular advantage of the process of the
invention that it can also be conducted in batch mode. Otherwise,
use may also be made of the regimes described in the German patent
application DE-A-196 28 142, page 4, lines 6 to 36.
In accordance with the invention, the copolymerization is conducted
in a microemulsion or miniemulsion, in particular a miniemulsion.
In this case the average particle diameter of the emulsified
monomer droplets is below 500 nm. It is preferably from 10 to 500
nm, more preferably from 50 to 400 nm, and with very particular
preference from 100 to 350 nm. The particle diameter is the
so-called z-average particle diameter, which is determined by means
of photon correlation spectroscopy in accordance with the principle
of dynamic, quasielastic light scattering. For this purpose use may
be made, for example, of a Coulter N4 Plus Particle Analyzer from
Coulter Scientific Instruments or a PCS Malvern Zetasizer 1000. The
measurement is normally made on an aqueous emulsion containing
0.01% by weight of the emulsified monomer droplets. The aqueous
emulsion further comprises, in the aqueous phase, the corresponding
monomers in dissolved form (up to saturation), so that the
emulsified monomer droplets do not break up.
The process of the invention may be performed so as to give the
bimodal particle size distribution described above. Methods of
producing bimodal particle size distributions are customary and
known in the technological field in question here. It is preferred
to use the seed method described in the German patent application
DE-A-196 28 142, page 5, lines 31 to 49.
The preparation of the miniemulsion as part of the process of the
invention has no particular features as to method, but instead
takes place in accordance with the customary and known methods of
dispersing or emulsifying in a high shear field. Examples of
suitable methods are described in the patents DE-A-196 28 142, page
5, lines 10 to 30, DE-A-196 28 143, page 7, lines 30 to 58, or
EP-A-0 401 565, [lacuna] lines 27 to 51.
An essential advantage of the primary dispersions of the invention
is that they can be used per se as coating materials of the
invention, preferably as surfacers, solid-color topcoat, aqueous
basecoat and clearcoat materials, in particular as clearcoat
materials. For these end uses, at least one customary and known
coatings additive (F) in effective amounts may be added to the
primary dispersions of the invention before, during and/or after
their preparation. Before or during the preparation of the primary
dispersions of the invention, the only coatings additives (F) added
are those which do not disrupt, or even totally inhibit, the
miniemulsion polymerization. The general technical knowledge of the
skilled worker allows him or her to identify such additives (F).
Preferably, said additives (F) are added after the preparation of
the primary dispersions of the invention.
Examples of suitable coatings additives (F) are pigments, as
described in Rompp Lexikon Lacke und Druckfarben, Georg Thieme
Verlag, 1998, pages 176, "Effect pigments"; pages 380 and 381
"Metal oxide-mica pigments" to "Metal pigments"; pages 180 and 181,
"Iron blue pigments" to "Black iron oxide"; pages 451 to 453,
"Pigments" to "Pigment volume concentration"; page 563, "Thioindigo
pigments"; and page 567, "Titanium dioxide pigments". These
additives (F) are used when the coating materials of the invention
are used as surfacers, solid-color topcoats or aqueous basecoats,
but in particular as aqueous basecoats in the context of the
so-called wet-on-wet technique (cf., for example, European patent 0
089 497), to produce multicoat color and/or effect paint
systems.
Further examples of suitable coatings additives (F), which may be
used both in the pigmented paints and in the unpigmented coating
materials, are oligomeric and polymeric, thermally curable, linear
and/or branched poly(meth)acrylates or acrylate copolymers of
block, comb and/or random structure, especially those described in
the patent DE-A-197 36 535, polyesters, especially those described
in the patents DE-A-40 09 858 or DE-A-44 37 535, alkyds, acrylated
polyesters, polylactones, polycarbonates, polyethers, epoxy
resinamine adducts, (meth)acrylate diols, partially hydrolyzed
polyvinyl esters, polyurethanes and acrylated polyurethanes, as
described in the patents EP-A-0 521 928, EP-A-0 522 420, EP-A-0 522
419, EP-A-0 730 613 or DE-A-44 37 535, or polyureas.
Further examples of suitable coatings additives (F) are organic and
inorganic fillers, thermally curable reactive diluents, low-boiling
and/or high-boiling organic solvents ("long solvents"), UV
absorbers, light stabilizers, free-radical scavengers, thermally
labile free-radical initiators, crosslinking catalysts,
devolatilizers, slip additives, polymerization inhibitors,
defoamers, emulsifiers, wetting agents, adhesion promoters,
leveling agents, film-forming auxiliaries, rheology control
additives, or flame retardants. Further examples of suitable
coatings additives are described in the textbook "Lackadditive" by
Johan Bieleman, Wiley-VCH, Weinheim, N.Y., 1998.
If the coating materials of the invention are to be curable with
actinic radiation as well (dual cure), they comprise additives (F)
curable with actinic radiation. Said actinic radiation may comprise
electromagnetic radiation such as near infrared (NIR), visible
light, UV light or X-rays, or corpuscular radiation such as
electron beams. Examples of suitable additives (F) curable with
actinic radiation are known from German patent DE-C-197 09 467.
In terms of method, the application of the coating materials of the
invention has no special features, but instead can be carried out
by all customary application methods, such as spraying, knife
coating, brushing, flow coating, dipping, trickle coating or roller
coating, for example. It is preferred to use spray application
methods, such as, for example, compressed air spraying, airless
spraying, high-speed rotation, electrostatic spray application
(ESTA), alone or in conjunction with hot spray application such as
hot air spraying, for example.
Suitable coating substrates are all surfaces which are not damaged
by curing of the coatings present on them with application of heat;
examples include metals, plastics, wood, ceramic, stone, textile,
fiber composites, leather, glass, glass fibers, glasswool and
rockwool, mineral-bound and resin-bound building materials, such as
plasterboard and cement slabs or roof shingles, and also assemblies
of these materials. Accordingly, the coating material of the
invention is also suitable for applications outside of automotive
finishing, especially in the coating of furniture and in industrial
coating, including coil coating, container coating and the
impregnation or coating of electrical components. In the context of
industrial coatings, it is suitable for coating virtually all parts
for private or industrial use, such as radiators, domestic
appliances, small metal parts such as nuts and bolts, hub caps,
wheel rims, packaging, or electrical components such as motor
windings or transformer windings.
In the case of electrically conductive substrates it is possible to
use primers produced in a customary and known manner from
electrodeposition (ED) coating materials. Suitable for this purpose
are both anodic (AED) and cathodic (CED) electrodeposition coating
materials, but especially CED. Unfunctionalized and/or apolar
plastic surfaces can be subjected to conventional pretreatment
before coating, such as with a plasma or by flaming, or may be
provided with an aqueous primer.
The method of curing the applied coating materials of the invention
also has no special features, but instead takes place in accordance
with the customary and known thermal methods such as heating in a
circulating air oven or irradiation with IR lamps, which in the
case of dual cure may be supplemented by exposure to actinic
radiation. In this context it is possible to use radiation sources
such as high-pressure or low-pressure mercury vapor lamps, which
may be doped with lead in order to open up a radiation window up to
405 nm, or electron beam sources.
The resultant coatings of the invention, especially the single-coat
or multicoat color and/or effect paint systems and clearcoat
systems of the invention, are easy to produce and have outstanding
optical properties and very high chemical resistance and weathering
stability. Accordingly, the substrates of the invention, comprising
at least one coating of the invention, are also of particularly
high service value and have a particularly long service life, which
makes them particularly attractive, economically and technically,
for producers and users.
EXAMPLES
Examples 1 to 4
The preparation of primary dispersions of the invention and of
coating materials of the invention by the process of the
invention
For carrying out Examples 1 to 4, first of all an emulsifier was
dissolved in water. Then olefinically unsaturated monomers (A),
diphenylethylene (B), a blocked polyisocyanate (C), and an
oil-soluble initiator were mixed with one another. The resultant
organic solution was converted into a milky emulsion using an
Ultraturrax at room temperature over the course of 4 seconds. The
resultant preemulsions were stable for several minutes, i.e., they
did not exhibit phase separation and hence could be processed
further to finely divided miniemulsions without problems by means
of a high-pressure homogenizing apparatus. For preparing the
miniemulsions of Examples 1 to 4 the individual preemulsions were
introduced into the storage vessel of a pressure release
homogenizer and were emulsified under maximum pressure in
circulation mode with cooling for 1 minutes. Following
emulsification, the miniemulsions of Examples 1 to 4 had particle
sizes in the range from 100 nm to 500 nm and contained 40% by
weight of monomer mixture and polyisocyanate (100%), based on the
total amount of the respective miniemulsion, and were stable on
storage for several weeks.
Table 1 gives an overview of the starting products used for the
miniemulsions of Examples 1 to 4, the amounts in which they were
used, and the z-average particle diameters of the monomer droplets,
which were determined by means of photon correlation spectroscopy
in accordance with the principle of dynamic, quasielastic light
scattering.
The miniemulsions of Examples 1 to 4 were transferred to suitable
steel reactors and heated slowly with stirring at from 80 to
90.degree. C. The miniemulsions were stirred at this temperature
until the solids content of the resultant primary dispersions 1 to
4 of the invention no longer rose. The primary dispersions of the
invention were sedimentation-stable for several weeks.
Table 1 gives an overview of the polymerization period, the
theoretical glass transition temperature Tg, calculated by the
method of Fox, of the copolymers present in the primary dispersions
of the invention, their hydroxyl number, their molecular weight and
their polydispersity of the molecular weight distribution, and also
the z-average particle diameters and the solids contents and pH
values of the primary dispersions of the invention.
The z-average particle diameters of the miniemulsions 1 to 4 and of
the primary dispersions 1 to 4 of the invention were measured using
a PCS Malvern Zetasizer 1000.
The primary dispersions of the invention from Examples 1 to 4 were
knife coated onto glass plates at a wet film thickness of 150 .mu.m
and were baked for 30 minutes at 145.degree. C., 160.degree. C. and
180.degree. C.
Table 1 gives an overview of important performance properties of
the resultant clearcoats of the invention from Examples 1 to 4.
The results demonstrate that the clearcoats of the invention have a
high solvent stability, a high gloss, and a smooth surface.
TABLE 1 Material composition and properties of the miniemulsions 1
to 4 of the invention, polymerization conditions, material
composition and properties of the primary dispersions 1 to 4 of the
invention, and important performance properties of the clearcoats 1
to 4 of the invention Example 1 2 3 4 Miniemulsion: Composition
(parts by weight): Emulsifier.sup.a) 0.521 0.521 0.521 0.521 Methyl
methacrylate 16.95 16.95 16.95 16.95 n-Butyl methacrylate 13.69
13.69 13.69 13.69 Styrene 15.32 14.99 14.34 13.04 Hydroxypropyl
methacrylate 18.25 18.25 18.25 18.25 Diphenylethylene 0.978 1.3
1.955 3.264 Blocked polyisocyanate.sup.b) 34.29 34.29 34.29 34.29
OH:NCO ratio 1:1 1:1 1:1 1:1 Particle diameter (nm) 151 144 153 151
Polymerization: Initiator.sup.c) (parts by weight per 100 parts by
weight of emulsifier, monomer mixture and blocked polyisocyanate)
3.26 3.26 3.26 3.26 Polymerization time (h) 10.5 7.0 17.5 11.0
Primary dispersion: Solids content.sup.d) (% by weight) 37.9 36.2
35.7 34.7 Particle diameter (nm) 143 154 154 153 pH 6.0 6.0 6.0 6.0
Sediment wet (g) 0 0 0 0 Copolymer: Number-average molecular 19.300
14.880 11.550 8.787 weight Mn.sup.e) (daltons) Mass-average
molecular 110.600 80.490 59.150 44.660 weight Mw.sup.e) (daltons)
Polydispersity Mw/Mn 5.73 5.41 5.18 5.08 Class transition
temperature 74.55 74.55 74.55 74.55 (theoretical according to Fox)
(.degree. C.) Hydroxyl number (mg KOH/g) 109 109 109 109 Clearcoat:
MEK-DR.sup.f) (145/160/180.degree. C.) 3/190/ 5/45/ 3/90/ 1/74/
>200 >200 >200 >200 Gloss (visual) high high high high
Surface texture.sup.g) (visual) 2 1 1 1 .sup.a) Sodium lauryl
sulfate, Texapon .RTM. from Henkel; .sup.b)
Dimethylpyrazole-blocked commercial polyisocyanate; .sup.c)
tert-Butyl peroxyethylhexanoate; .sup.d) 130.degree. C., one hour;
.sup.e) Measured by gel permeation chromatography using polystyrene
as internal standard; .sup.f) Number of double rubs with a cotton
pad soaked with methyl ethyl ketone; .sup.g) Rating: 1 = good, 2 =
satisfactory, 3 = poor;
Examples 5 and 6
The preparation of primary dispersions of the invention and
production of clearcoats of the invention by the process of the
invention
For carrying out Examples 5 and 6, the process of Example 2 was
repeated but using the water-soluble initiator ammonium
peroxodisulfate instead of the oil-soluble initiator tert-butyl
peroxyethylhexanoate. Additionally, in Example 5, the miniemulsion
and the 24% strength aqueous ammonium peroxodisulfate solution were
metered in as two separate feed streams simultaneously over a
period of two hours. Additionally, in Example 6, the miniemulsion
was introduced as initial charge at 80.degree. C. and stirred, and
the 24% strength ammonium peroxodisulfate solution was added
dropwise at a uniform rate over the course of two hours. The
miniemulsions 5 and 6 contained 35% by weight of monomer mixture
and polyisocyanate (100%), based on the total amount of the
respective miniemulsion, and were stable on storage for several
weeks.
Table 2 gives an overview of the starting products and their
amounts and also the results of the experiments.
TABLE 2 Material composition and properties of the miniemulsions 5
and 6 of the invention, polymerization conditions, material
composition and properties of the primary dispersions 5 and 6 of
the invention, and important performance properties of the
clearcoats 5 and 6 of the invention Example 5 6 Miniemulsion:
Composition (parts by weight): Emulsifier.sup.a) 0.2 0.2 Methyl
methacrylate 17.0 17.0 n-Butyl methacrylate 13.73 13.73 Styrene
15.04 15.04 Hydroxypropyl methacrylate 18.31 18.31 Diphenylethylene
1.31 1.31 Blocked polyisocyanate.sup.b) 34.4 34.4 OH:NCO ratio 1:1
1:1 Particle diameter (nm) 210 210 Polymerization: Initiator.sup.c)
(parts by weight per 100 parts by weight of emulsifier, monomer
mixture and blocked polyisocyanate) 1.96 1.96 Polymerization time
(h) 4.0 3.0 Primary dispersion: Solids content.sup.d) (% by weight)
32.7 34.4 Particle diameter (nm) 273 314 pH 3.6 3.1 Copolymer:
Number-average molecular weight Mn.sup.e) (daltons) 11.740 12.020
Mass-average molecular weight Mw.sup.e) (daltons) 19.830 20.660
Polydispersity Mw/Mn 1.69 1.72 Glass transition temperature 74.55
74.55 (theoretical according to Fox) (.degree. C.) Hydroxyl number
(mg KOH/g) 109 109 Clearcoat: MEK-DR.sup.f) (145/160/180.degree.
C.) 78/200/ 81/200/ >200 >200 Surface texture.sup.g) (visual)
2 2 .sup.a) Sodium lauryl sulfate, Texapon .RTM. from Henkel;
.sup.b) Dimethylpyrazole blocked commercial polyisocyanate; .sup.c)
100% strength ammonium peroxodisulfate; .sup.d) 130.degree. C., one
hour; .sup.e) Measured by gel permeation chromatography using
polystyrene as internal standard; .sup.f) Number of double rubs
with a cotton pad soaked with methyl ethyl ketone; .sup.g) Rating:
1 = good, 2 = satisfactory, 3 = poor;
The results demonstrate the particularly high solvent resistance of
the clearcoats 5 and 6 of the invention.
* * * * *